We evaluated systolic and diastolic blood pressure, heart rate variability and skin conductance at baseline, and 1 and 4 months in 38 participants with elevated blood pressure, randomly assigned to expressive writing or control groups. There was a significant interaction such that the very low frequency wave of heart rate variability increased over time only in controls, suggesting potentially protective buffering in expressive writing. Systolic and diastolic blood pressure also decreased significantly from baseline to 1 month in expressive writing. Consistent with inhibition, Anger-In moderated effects of writing on 4-month DBP. Overall, expressive writing demonstrated short-term autonomic benefits and longer-term moderated effects.